“Looks as if they were going to leave,” whispered Fred excitedly. “Maybe they are going out into the open for some fresh air. I can’t blame them for that,” he added, for throughout the cavern there was a strong smell of used gasoline.
Five minutes passed, and then one by one the Germans walked away from the submarine. They did not come in the direction of the cadets, but passed around another bend of the rocks, and so out of sight.
“That must be the way used by that fellow we saw in the forest,” declared Jack.
All but three of the electric lights had been put out, so that the interior of the cavern was now quite gloomy. The only sound that broke the stillness was the soft lap, lap of some distant waves, evidently where they broke on the shore of the bay close to the larger entrance of the cavern.
“I’d like to bet that the entrance is under water,” said Fred. “If it was at the surface some one would have discovered this place a long time ago.” And in this surmise the youngest Rover was correct. The passageway, which was amply large, was over ten feet below the surface of the bay even at low tide.
“Do you suppose they’ve all left the submarine?” whispered Gif presently. With the intense silence prevailing, they felt that they must be very cautious in making any noise.
“That’s hard to say,” answered Jack, with a shrug of his shoulders.
“It looks so to me,” put in Fred. “I don’t believe any of those fellows would care to stay down here unless it was necessary. They have stopped all the engines and things like that. I guess those electric lights are burning simply from a storage battery.”
The three cadets waited for another ten minutes, and then, as no one appeared, and as the submarine seemed to be deserted, they stole forward cautiously, all anxious to get a closer look at the U-boat.
“If we could only throw a chain around the propellers, or something like that, maybe it would keep them from getting away if they tried to run for it,” said the young captain.